1. Conducted and Wireless Media (Part I)
School of Business
Eastern Illinois University
Conducted and Wireless Media (Part I)
(October 5, 2015)
© Abdou Illia, Fall 2015

2. Learning Objectives Outline characteristics of conducted media
Select conducted media in LAN design

3. Major categories of Media
Conducted Media
Physically connect network devices
Wireless Media
Use electromagnetic waves/radiation

4. Conducted Media
Twisted Pair cable
Coaxial cable
Optical Fiber cable

5. Twisted Pair wire
Shielded Twisted Pair (STP) Versus Unshielded Twisted Pair (UTP)
Typically 2 or more Twisted pair wires & different standards for different applications

6. Twisted Pair wire 2
Q: Are Shielded Twisted Pairs (STP) affected by interference ?

7. Coaxial cable
A single wire wrapped in a foam (or plastic) insulation surrounded by a braided metal shield, then covered in a plastic jacket
Cable can be thick or thin
Provides for wide range of frequencies

8. Less noise/interference compared to twisted pairs
Coaxial cable
Two major coaxial technologies:
Baseband Coaxial tech.
Broadband Coaxial tech.
Uses digital signaling
Transmits anal./digital signals
One channel of digital data
Multiple channels of data
~1 kilometer w/o repeater
~ 4 kilometer w/o repeater
Thin coaxial cable
Typically used for digital data transmission in Ethernet LANs
Typically used for baseband transmission
Thick coaxial cable
Typically for broadband transmission
Typically used for video transmission
Less noise/interference compared to twisted pairs

9. Baseband transmission
Coaxial cable
Coaxial cable standards:
Type①
Ohm rating②
Use
RG-11
75 ohm
Used in 10Base5 Ethernet (known as Thick Ethernet)
RG-58
50 ohm
Used in 10Base2 Ethernet
RG (Radio Guide) specifies characteristics like wire thickness, insulation thickness, electrical properties, etc.
Ohm is the measure of resistance within the medium
10Base5
Speed:
10 Mbps
Distance:
500 meters
Signal type:
Baseband transmission

10. Fiber Optic
A thin glass cable approximately a little thicker than a human hair
Two concentric layers termed Core and Cladding
Cladding
Core
Common types:
62.5/125 microns
50/125 microns

11. Fiber Optic Photo diode Photo receptor (LED or LD) (LED or LD)
Source
Destination
Photo diode
(LED or LD)
Photo receptor
(LED or LD)
Fiber optic cable
Photo diode (light/laser source) at the transmitting end
Generate light/laser and modulate it to represent binary data received from Source
Photo receptor (optic sensor) at the receiving end
Receive the light/laser and convert it into digital signal

12. Fiber Optic Many advantages over Twisted pair and Coaxial cable
Speed
No significant noise
No interference
Less signal attenuation, i.e. longer distance
Low-power transceivers could be used (less electric consumption)
Typical use in Businesses

13. Conducted Media

14. Case study The following figure shows a common situation in LANs.
Remember :
Using Category 5 UTP, the maximum segment length is 100 meters.
A wall jack is a passive device that does not regenerate signals
Cat 5-UTP
Crossover cable

15. Case study
Cat 5-UTP
Crossover cable
What kind of problem there will be if the distance between the Workstation and the Hub is more than 100 meters? What solution can be applied ?
If the cable that connects the workstation and the hub passes through a noisy environment (Heating or cooling mechanical room) what action could be taken to prevent interference?

16. Case study
Cat 5-UTP
Crossover cable
If the needed data rate is higher than 100 Mbps, what are the possible solutions?

17. Summary Questions
What does cross talk interference mean ? How can crosstalk interference be reduced ?
If transmission wires are placed side by side, electromagnetic radiation is emitted by one wire and picked up by the other. Twisting pair of wire reduce crosstalk interference.
What categories of twisted pair are usually used in LANs ?
Categories 3, 4, 5, 6, 7, 8
What are the advantages and disadvantages of STP compared to UTP ?
Advantage: better level of isolation from interference. Disadvantage: cost
What is the main difference between baseband coaxial cable and broadband coaxial cable ?
Baseband carries digital signals with a single channel. Broadband carries analog or digital signals with multiple channels.
What are the advantages of Optical fiber compared twisted pair and coaxial cable ?
Speed, No significant noise, No interference, Long distance
Can you transmit video signal over twisted pair wire ? Explain
You can. Noise used to be a limitating factor, but it’s no longer the case.

18. Baseband signaling Single transmission channel Only one bit at a timef e
space $
Single transmission channel
Only one bit at a time
Uses TDM (Time Division Multiplexing)
Time
Voltage 1 1 1

19. Broadband signaling Multiple transmission channelsf e
Multiple transmission channels
Multiple bits at a time
Uses FDM (Frequency Division Multiplexing)